AU-Module-2-PSY-003.pdf

LEARNING MODULE A Course Pack in Physiological Psychology (PSY 003) DR. JINAMARLYN B. DOCTOR, RPM  TABLE OF CONTENTS Module 2: Foundations of Biopsychology.................................. 1 Topic O...

LEARNING MODULE A Course Pack in Physiological Psychology (PSY 003) DR. JINAMARLYN B. DOCTOR, RPM  TABLE OF CONTENTS Module 2: Foundations of Biopsychology.................................. 1 Topic Outline.................................. 1 Introduction.................................. 1 Target Learning Outcomes.................................. 1 Activities.................................. 1 Analysis.................................. 2 Abstraction.................................. 2 Lesson 1: Neurons and Synapses.................................. 2 The Cells of the Nervous System.................................. 2 The Nerve Impulse.................................. 6 Generation, Conduction, and Integration of.................................. 7 Postsynaptic Potentials Neurotransmitters and Receptors.................................. 11 Synapses, Drugs and Addiction................................... 13 Lesson 2: Nervous System and the Brain.................................... 14 General Layout of the Nervous System................................... 14 Anatomy of the Central Nervous System................................... 17 Application.................................. 20 Assessment.................................. 20  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE MODULE 2: Foundations of Biopsychology Lesson 1: Neurons and Synapses I. The Cells of the Nervous System II. The Nerve Impulse III. Generation, Conduction, and Integration of Postsynaptic Potentials IV. Neurotransmitters V. Drugs and Behavior Lesson 2: Nervous System and the Brain I. General Layout of the Nervous System II. Anatomy of the Central Nervous System This module will cover the anatomy of neurons as well as their function, which includes how neurons conduct and transmit electrochemical impulses throughout your nervous system. It starts with a description of how signals are generated in resting neurons, followed by a description of how signals are transmitted via neurons. Finally, we'll go through how medicines are used to investigate the relationship between synaptic transmission and behavior. Furthermore, in order to grasp what the brain does, one must first understand what it is - the names and locations of its primary components, as well as how they are connected to one another. After the successful completion of this module, the student must be able to: Draw a diagram of a neuron's structure and explain what each portion does. Describe the function of the blood-brain barrier. Recognize the neuron's resting potential. Talk about how postsynaptic potentials are generated, transmitted, and integrated. Identify and characterize the nervous system's major divisions. Draw a diagram of the brain's major areas and structures. 1. The major elements of a multipolar neuron and the brain should be drawn, labeled, and defined. Make a note of your response in your Course Portfolio. 2. React to the following statement: Drugs' effects on an individual's conduct. In your Course Portfolio, write down your reaction. 3. Make a poll to see how men and women differ the most in terms of intellect, performance, and other factors. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 1  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE 1. What is the name for a neuron's extensively branching structure? What do you call the long, thin structure that transmits information from one cell to another? 2. Recognize the four major structures that make up a neuron. 3. Describe the blood–brain barrier and the functions it performs. 4. Are sodium ions more concentrated within or outside the cell when the membrane is at rest? Where do the potassium ions have a higher concentration? 5. Do sodium ions migrate into or out of the cell when the action potential rises? Why? LESSON 1: NEURONS AND SYNAPSES I. The Cells of the Nervous System Neurons and glia are the two types of cells that make up the nervous system. Glia serve a variety of tasks that are difficult to summarize. Neurons receive information and pass it to other cells, and Glia serve a variety of functions that are difficult to summarize. Santiago Ramon y Cajal demonstrated in the late 1800s that a small space separates the ends of one neuron's fiber from the surface of the next neuron using newly acquired staining techniques. Individual cells make up the brain, just like the rest of the body. Structure of an Animal Cell Neurons share a lot of characteristics with the rest of the body's cells. The cell's membrane (or plasma membrane) is the structure that divides the cell's inside from the external environment. It's made up of two layers of fat molecules that can freely flow around each other. Although most molecules are unable to pass through the membrane, specialized protein channels allow for the controlled passage of water, oxygen, sodium, potassium, calcium, chloride, and other Embedded in the membrane are protein channels that permit essential compounds. certain ions to cross through the membrane at a controlled rate. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 2  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Structure of a Neuron The form of neurons is the most distinguishing trait, because it varies greatly from one neuron to the next. Neurons, unlike most other cells in the body, have lengthy branching extensions. These components can be found in bigger neurons: Presynaptic terminals, dendrites, a soma cell (cell body), and an axon. (Axons and well-defined dendrites are absent in the tiny neurons.) Contrast the motor and sensory neurons. The soma of a motor neuron is located in the spinal cord. It gets excitation from other neurons via its dendrites and transmits impulses to a muscle via its axon. At one end, a sensory neuron is specialized to be highly sensitive to a stimuli, such as light, sound, or touch. Dendrites are branching fibers that get narrower near their ends. (The term dendrites come from a Greek root word meaning “tree”). The surface of the dendrite is lined with specific synaptic receptors, which receive information from other neurons. A dendrite's surface area determines how much information it can receive. Some dendrites have a lot of branches and thus a lot of surface area. Many have dendritic spines, which are small outgrowths that increase the accessible surface area for connections. The cell body or soma (Greek for “body”; pl: somata), contains the nucleus, ribosomes, and mitochondria. Neuron cell bodies vary in size from 0.005 mm to 0.1 mm in mammals and up to a millimeter in some invertebrates. The axon is a thin fiber of constant diameter, in most cases longer than the dendrites. (The tern axon comes from a Greek word meaning “axis”). The axon is the information sender of the neuron, sending impulses to neighboring neurons, organs, and muscles. Many axons in the vertebrae are surrounded by an insulating substance termed a myelin sheath, which has nodes of Ranvier (RAHN-vee-ay). Myelin sheaths do not exist in invertebrate axons. Each branch of an axon swells at its tip to create a presynaptic terminal, also known as an end bulb or buoton (French for "button"). This is the point at which the axon releases substances that pass the neuron-to-neuron junction. Other terms for neurons include: An afferent axon transports information into a structure, while an efferent axon transports information out of it. Every motor neuron is an efferent from the nervous system, while every sensory neuron is an afferent to the rest of the nervous system. A neuron is an efferent from one structure and an afferent from another inside the nervous system. (Efferent begins with an e, as in exit; afferent begins with an a, as in admit.) An axon may be efferent from the thalamus and afferent from the cerebral cortex, for example. A cell is an interneuron or intrinsic neuron of a structure if its dendrites and axon are totally enclosed within that structure. An intrinsic thalamic neuron, for example, has its axon and all of its dendrites within the thalamus. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 3  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Glia The other primary components of the nervous system, glia (or neuroglia), do not convey information over vast distances like neurons do, but they do conduct many additional activities. Glia is derived from a Greek word that means "glue," and it was thought by early researchers that glia kept the neurons together like glue. Despite the fact that the premise is no longer valid, the phrase lives on. Glia are smaller than neurons, but they are more numerous. Several types of Glia with different functions: 1. Astrocytes – A star-shaped wrap around a set of functionally linked axons' presynaptic terminals. By absorbing ions emitted by axons and returning them to them, they are able to relay messages in waves. Astrocytes also control the amount of blood flow to each brain location and eliminate waste material formed when neurons die. Another job of astrocytes is to widen blood arteries in certain brain locations during periods of increased activity, allowing more nutrients to enter that area. Another proposed function is shrouded in mystery: Neurons communicate with one another by producing transmitters like glutamate. When a neuron releases a large amount of glutamate, neighboring glia cells absorb some of it. 2. Microglia — tiny cells that eliminate both material and viruses, fungus, and other microbes. They act as if they were a member of the immune system. 3. Oligodendrocytes (OL-i-go-DEN-druh-sites) in the brain and spinal cord. 4. Schwann cells - Schwann cells are specialized forms of glia that build the myelin sheaths that surround and insulate specific vertebrate axons. They are found on the periphery of the body. 5. Radial glia - During embryonic development, radial glia direct the migration of neurons, their axons, and dendrites. The majority of radial glia differentiate into neurons after embryological development, while a lesser proportion differentiate into astrocytes and oligodendrocytes. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 4  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE The Blood-Brain Barrier: Why we need a Blood-Brain Barrier The blood-brain barrier is a barrier that keeps most substances out of the brain of vertebrates. Many substances cannot travel from the blood to the brain, despite the fact that the brain, like any other organ, requires nutrition from the blood. When a virus infects a cell, internal mechanisms extrude virus particles over the membrane, allowing the immune system to detect them. When immune system cells detect a virus, they kill the virus as well as the cell that houses it. A cell that exposes a virus through its membrane is effectively saying to the immune system, "Look, immune system, I'm infected with this virus." “Kill me so the others can live.” A virus that enters your nervous system is likely to stay with you for the rest of your life. The virus that causes chicken pox and shingles, for example, can penetrate spinal cord cells. Virus particles persist in the spinal cord, where they can resurface decades later, no matter how well the immune system destroys the virus outside the neurological system. The virus that causes genital herpes is the same way. How the Blood-Brain Barrier Works The endothelial cells that line the capillary walls are responsible for forming the blood-brain barrier. Such cells are separated by microscopic gaps outside the brain, but inside the brain, they are so densely connected that almost nothing travels between them. The brain has several mechanisms: 1. Small uncharged molecules, such as oxygen and carbon dioxide, can freely cross one other. Water passes through endothelial cells' walls via specific protein channels. 2. Molecules that dissolve in the membrane's lipids cross passively as well (for example, vitamins A and D, as well as any medications that impact the brain, such as antidepressants and other psychiatric drugs, as well as criminal substances like heroin). Active transport is a protein-mediated process in which the brain expends energy to pump substances from the blood into the brain. Glucose (the brain's main fuel), amino acids (protein building blocks), purines, choline, a few vitamins, iron, and certain hormones are all actively carried into the brain. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 5  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE The blood-brain barrier plays an important role in human health. Endothelial cells lining the brain's blood vessels atrophy in persons with Alzheimer's disease or comparable disorders, allowing dangerous substances to reach the brain. The barrier, on the other hand, creates a problem in medicine because it prevents many medications from entering. Because nearly all chemotherapy medications fail to cross the blood-brain barrier, brain tumors are difficult to treat. II. The Nerve Impulse Resting Potential of the Neuron A membrane roughly 8 nanometers (nm) thick (less than 0.00001 mm) covers all regions of a neuron and is made up of two layers (an inner layer and an outer layer) of phospholipid molecules (containing chains of fatty acids and a phosphate group). Cylindrical protein molecules embedded within the phospholipids allow various substances to pass through. The membrane's structure gives it a mix of flexibility and stiffness, and it regulates the passage of chemicals between the interior and outside of the cell. A difference in electrical charge between the inside and outside of the cell is known as an electrical gradient, also known as polarization. Because of negatively charged proteins inside the cell, the neuron inside the membrane has a slightly negative electrical potential compared to the outside. The resting potential is the voltage differential in a resting neuron. Researchers used a very thin microelectrode placed into the body to determine the resting potential. The electrode's diameter must be as small as feasible in order for it to penetrate the cell without causing damage. A fine glass tube filled with a concentrated salt solution and tapering to a tip diameter of 0.0005 mm or less is the most typical electrode. The circuit is completed by a reference electrode located outside the cell. The interior of the neuron exhibits a negative potential when the electrodes are connected to a voltmeter. -70 millivolts (mV) is a common threshold, however it varies from neuron to neuron. Ionic Basis of the Resting Potential Ions are positively and negatively charged particles that form when salts in brain tissue separate. In neurons, there are many different types of ions, but only two will be covered here: The Latin names for sodium PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 6  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE ions (Na+) and potassium ions (K+) are natrium (Na) and kalium (K) (K). Each Na+ and K+ ion has a single positive charge, as shown by the plus signs. In resting neurons: Outside the cell, there are more Na+ ions than inside, and inside, there are more K+ ions than outside. Even though ions can pass via specific pores called ion channels in neuronal membranes, these uneven distributions of Na+ and K+ ions are maintained. The transit of ions (e.g., Na+ or K+) is customized for each type of ion channel. Na+ ions are under a lot of pressure to get into resting neurons. There are two forms of pressure: 1. The electrostatic pressure of the resting membrane potential: The -70 mV charge draws positively charged Na+ ions into resting neurons because opposing charges attract. 2. The force that causes Na+ ions to travel down their concentration gradient due to random motion. The membrane potential is the key to understand how neurons work and how they malfunction. It is defined as the difference in electrical charge between the inside and the outside of a cell. Ion transport is carried out by processes in the cell membrane, which exchange three Na+ ions inside the neuron for two K+ ions outside on a regular basis. Sodium-potassium pumps are the common name for these transporters. Several more families of transporters (mechanisms in a cell's membrane that actively transport ions or molecules across the membrane) have been found since the discovery of sodium potassium pumps. III. Generation, Conduction, and Integration of Postsynaptic Potentials When neurons fire, chemicals called neurotransmitters are released from their terminal buttons and diffuse across synaptic clefts, where they bind with specific receptor molecules on the receptive membranes of the next neurons in the circuit. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 7  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Postsynaptic receptors have two effects: 1. Depolarize – the receptive membrane (for example, by lowering the resting membrane potential from -70 to -67 mV); 2. Hyperpolarize – this is a good thing to do (increase the resting membrane potential, from -70 to -72 mV, for example). Postsynaptic depolarizations, also known as excitatory postsynaptic potentials (EPSPs), increase the likelihood of a neuron firing. Inhibitory postsynaptic potentials (IPSPs) are another type of postsynaptic hyperpolarization that reduces the likelihood of a neuron firing. PSPs have three key characteristics: 1. They are graded (i.e. their amplitude proportional to intensity of input - stronger stimuli produce bigger EPSPs and IPSPs) 2. They are communicated in a decremental manner (as they spread passively from their point of origin (a synapse), becoming weaker as they go, similar to how sound travels through air). 3. They are quickly transmitted (like electricity through a cable, so rapidly that transmissions are usually regarded as being instantaneous). Generation of Action Potentials When a neuron is depolarized to the point where the membrane potential at the hillock reaches roughly – 65 mV, action potentials (AP; firing; spikes) are triggered at the axon hillock; this is the threshold of excitation for many neurons (umbral). APs, unlike EPSPs and IPSPs, aren't graded; they're either all or nothing (they occur full blown or not at all). Most neurons receive hundreds of synaptic contacts, and what happens at any given synapse has little impact on the neuron's activity. The sum (integration) of what happens at multiple presynaptic neuron synapses determines whether or not a neuron fires. Neural integration can be divided into two types: 1. Spatial Summation (EPSPs + EPSPs; IPSPs + IPSPs; EPSPs + IPSPs); and 2. Temporal Summation (EPSPs + EPSPs; IPSPs + IPSPs) Spatial and temporal summation occur constantly in a working neuron; synapses closer to the axon hillock have a greater impact on firing due to the decremental transmission of postsynaptic potentials. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 8  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Ionic Events Underlying Action Potentials When the excitation threshold is reached, voltage-gated Na+ channels open momentarily, and Na+ ions rush into the neuron under tremendous pressure due to both the concentration gradient and the electrostatic gradient: this drives the membrane potential to about +50 millivolts, at which point K+ channels open momentarily, and K+ ions are driven out of the neuron by the +50 millivolt charge and by their high internal concentration. Because only a few ions adjacent to the membrane are involved in the generation of an action potential, the neuron is repolarized and slightly hyperpolarized for a few milliseconds; the +50 millivolt charge also draws some C ions into the neuron. Because only a few ions adjacent to the membrane are involved in the generation of an action potential, the resting potential is easily reestablished by the random motion of ions. Conduction of Action Potentials The purpose of axons is to transmit APs from the soma to the terminal buttons of the neuron. Transmission of all-or-none APs along an axon is not like transmission of graded postsynaptic potentials; transmission of EPSPs and IPSPs is passive (like electricity through a cable), thus it is instantaneous and decremental; While an AP's transmission along an axon is active, it is slower and nondecremental. Consider the axon as a row of voltage-gated sodium channels: when voltage-gated sodium channels on the hillock membrane open, Na+ ions rush in and a full-blown AP is generated; the electrical disturbance thus created is passively transmitted to the next sodium channels along the axon, and they open like trap doors, allowing another full-blown potential to be generated. Because sodium channels are so densely packed, it's better to think of APs as waves of depolarization propagating along an axon - because AP conduction is a dynamic process. There are two major distinctions between the conduct of APs and the conduct of PSPs: 1. AP conduction is slower; and 2. AP conduction is nondecremental, meaning that APs formed at the hillock are the same size as those generated at the end of the axon. Because the ion channels in the cell body and dendrites are chemical-gated rather than voltage-gated, transmission of action potentials through cell bodies and dendrites is passive. Many of the neurons in the CNS have no axons; they are interneurons; they have no action potentials; they are small, difficult to study, and they have no axons; in the human visual system, for example, incoming impulses pass through four layers of neurons before reaching one with an axon. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 9  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Anterograde transmission refers to transmission in the typical path (orthodromic stimulation) from the hillock to the buttons; however, if the buttons are electrically stimulated, APs can be created and actively sent back to the hillock; this is known as retrograde transmission (antidromic stimulation). Many axons in the CNS and PNS are myelinated by oligodendroglia and Schwann cells; myelination insulates the semipermeable axon membrane, preventing the flow of ions through the axon except at the nodes of Ranvier; ironically, this enhances transmission. APs travel passively (decrementally and swiftly) between the nodes of Ranvier in myelinated axons, but there is a "stop" at each node while a full-blown AP is formed. Because much of the transmission of APs in myelinated axons is passive (from node to node), transmission in myelinated axons is faster and needs less energy. Axons that are larger conduct quicker than those that are smaller, and myelinated axons conduct even faster: 1. A large myelinated mammalian axon (e.g., sensory and motor neuron axons with a diameter of 0.015 mm) transmits at around 100 meters per second (about 224 miles per hour), 2. Small unmyelinated mammalian axons conduct at a rate of around 1 meter per second (2.24 miles per hour); and 3. Unmyelinated squid giant motor axons (diameter = 0.5 mm) conduct at 25 meters per second (56 mph) Refractory Periods Another action potential cannot be elicited at the same neuron for a brief period of time (about 1 millisecond) after the onset of an action potential, no matter how intense the stimulation; this period is known as the absolute refractory period - a wave of "absolute refractoriness" spreads down the axon behind the action potential.; a portion of the membrane that has just participated in the transmission of an action potential is unable to fire until it has been repolarized. Because the absolute refractory period is about 1 millisecond, neurons cannot normally fire more than 1,000 times per second after the absolute refractory period. There is a period of time after the absolute refractory period during which the neuron can fire again, but it takes a higher than normal level of stimulation to do so; this is called the refractory period. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 10  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Reuptake and Enzymatic Degradation One of two processes deactivates it in the synapse: 1. The enzyme acetylcholinesterase was discovered to break down acetylcholine in the synapse, and it was presumed that enzymes destroyed all neurotransmitters; 2. It appears that all other neurotransmitters are deactivated and regenerated by reuptake into the presynaptic neuron. IV. Neurotransmitters and Receptors A neuron produces chemicals at a synapse that affect another neuron. Neurotransmitters are the substances in question. A hundred or more substances are thought to be neurotransmitters or are suspected to be neurotransmitters. Two types of neurotransmitters: 1. Large molecule neurotransmitters are produced gradually in response to overall increases in neuron activity; their effects are usually extensive since they are frequently released into extracellular fluid, ventricles, or the circulation; they are hypothesized to act as neuromodulators. 2. Small-molecule neurotransmitters have punctate, point-to-point actions; when an action potential hits a button, they are released in a pulse into synaptic clefts. In the cytoplasm of terminal buttons, they are produced. Postsynaptic neurons are differentially influenced based on the receptor subtype: 1. Ion-channel related receptors chemically open or shut an ion channel, causing a fast-acting postsynaptic potential. 2. G-protein linked receptors consist of a protein chain that winds in and out of the cell membrane seven times and each is located next to a guanine sensitive protein. G-protein linked receptors are more common than ion-channel related receptors, and they are slower acting, longer lasting, and more diffuse. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 11  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Major categories of neurotransmitters: a. Amino Acid Neurotransmitters acids containing an amine group (NH2), also the individual building blocks of proteins; they also serve as the transmitters at fast-acting, point-to-point synapses. Glutamate, aspartate, glycine, and gamma-aminobutyric acid (GABA) are neurotransmitters, according to conclusive evidence. We acquire glutamate, aspartate, and glycine from the proteins we consume, and glutamate is used to make GABA, hence nutrition is crucial for "good" neurotransmission. b. Monoamine Neurotransmitters are formed by slight modification to amino acid molecules; thus the name "monoamine" (one amine). Monoamines are produced from string-of-beads axons and have gradual, lingering, dispersed effects; monoamine-releasing neurons often contain cell bodies in the brain stem (e.g., the nigrostriatal dopamine pathway). c. Acetylcholine (a one-member “family”) a chemical like an amino acid, except that it includes an N(CH3)3 group instead of an NH2. It's a small molecule transmitter found at neuromuscular junctions, many ANS synapses, and some CNS synapses; it's made by adding an acetyl group to a choline molecule, hence the name; it's the only neurotransmitter known to be deactivated in the synapse by enzymatic degradation rather than reuptake; it's deactivated by (acetylcholinesterase) (ACHE). d. Neuropeptide Transmitters are short chains of 10 or fewer amino acids; about 40 or 50 peptides are putative neurotransmitters; they are the largest neurotransmitters. Many peptides are released into the bloodstream by endocrine glands as well as neurons, resulting in far-reaching diffuse effects. Peptides are made by cleaving polypeptide chains comprising 10 to 100 amino acids; proteins are chains with more than 100 amino acids. Neuropeptides are hypothesized to serve as neuromodulators, adjusting the sensitivity of neurons to fast- acting point-to-point neurotransmitters. Coexistence (neuropeptides and small-molecule neurotransmitters are released from the same neurons); before, it was considered that each neuron emitted just one neurotransmitter. e. Purines a category of chemicals including adenosine and several of its derivatives. f. Gases nitric oxide and possibly others. Nitric oxide (chemical formula NO), a gas generated by many small local neurons, is the strangest transmitter. (NO is not to be confused with N2O, which is frequently referred to as "laughing gas.") In large quantities, nitric oxide is dangerous and difficult to produce in a laboratory. However, many neurons have an enzyme that allows them to manufacture it quickly. One of nitric oxide's unique functions is to regulate blood flow: When a part of the brain becomes very active, blood flow to that part of the brain increases. How does blood "know" which parts of the brain have grown more active? Nitric oxide sends the message. When neurons are PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 12  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE activated, they emit nitric oxide. Nitric oxide not only affects other neurons, but it also dilates adjacent blood vessels. V. Synapses, Drugs and Addiction Drug Mechanisms Ø An agonist is a medication that raises activity at a synapse (the phrase comes from the Greek word “contestant”), whereas an antagonist is a medicine that decreases activity (it is an anti-agonist or member of the opposing team). Drugs have a variety of effects, depending on their affinity (ability to bind to a receptor) and efficacy (tendency to activate it). Stimulant drugs boost energy, alertness, and activity while also improving mood and reducing weariness. Amphetamine and cocaine increase the amount of dopamine in the presynaptic terminal, which stimulates dopamine synapses in the nucleus accumbens and elsewhere. Nicotine is a compound present in tobacco, stimulates a family of acetylcholine receptors, conveniently known as nicotinic receptors. Opiates derived from , or chemically similar to those derived from, the opium poppy. Morphine, heroin, and methadone are examples of common opiates. Opiates help people relax and pay less attention to difficulties in the actual world. Marijuana leaves contain the chemical tetrahydrocannabinol and other cannabinoids. The amplification of sensory perception and the feeling that time has slowed are two common psychological effects of marijuana. Hallucinogenic Drugs Hallucinogenic medications are those that cause perceptional distortions. The following are some examples: Chemically, lysergic acid diethylamide (LSD) is similar to serotonin. At modest doses, the stimulant methylenedioxymethamphetamine (MDMA or ecstacy) increases dopamine release and produces effects comparable to amphetamine or cocaine. Alcohol and Alcoholism Alcohol has a variety of effects on neurons, including facilitating responsiveness at the GABAA receptor, PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 13  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE the brain's principal inhibitory site. It inhibits glutamate receptor activity, the brain's primary excitatory location (Tsai et. al., as cited in Kalat, 2013). The habitual use of alcohol despite medical or social consequences is referred to as alcoholism or alcohol dependency. Ø The activity of axons that release dopamine in the nucleus accumbens is increased by reinforcing brain stimulation, reinforcing experiences, and self-administered medications. Ø Although it plays a role in both, activity in the nucleus accumbens probably contributes more to "wanting" than "liking." Because the amount of pleasure decreases during addiction, addiction is mainly focused on "wanting." Ø Addicts learn to cope with stress by engaging in an addictive behavior. Lesson 2: NERVOUS SYSTEM AND THE BRAIN To comprehend what the brain does, it is necessary to first comprehend what it is—to know the names and locations of its major components, as well as how they are connected. It will provide you a basic understanding of brain anatomy. I. General Layout of the Nervous System and Cells of the Nervous System Two divisions of the Nervous System: 1. The Central Nervous System (CNS) is a part of the nervous system that is housed in the skull and spine. 2. The Peripheral Nervous System (PNS) is a division of the nervous system that is found outside of the skull and spine. The central nervous system is composed of two divisions: 1. The brain is the part of the CNS located in the skull 2. The spinal cord is the part located in the spine. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 14  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE Two divisions of Peripheral Nervous System (PNS): 1. The somatic nervous system (SNS) is the component of the central nervous system (CNS) that interacts with the outside world. It is made up of afferent nerves that carry sensory messages to the central nervous system from the skin, skeletal muscles, joints, eyes, and ears, and efferent nerves that convey motor impulses from the central nervous system to the skeletal muscles. 2. The autonomic nervous system (ANS) manages the body's internal environment and is a part of the peripheral nervous system. Afferent nerves carry sensory messages from internal organs to the CNS, while efferent nerves carry motor signals from the CNS to internal organs. Note: the terms afferent and efferent if you remember that many words that involve the idea of going toward something—in this case, going toward the CNS—begin with an a (e.g., advance, approach, arrive) and that many words that involve the idea of going away from something begin with an e (e.g., exit, embark, escape). Two kinds of efferent nerves of the Autonomic Nervous System: 1. Sympathetic nerves are autonomic motor nerves that originate in the CNS and go through the lumbar (lower back) and thoracic (chest) areas of the spinal cord. 2. Parasympathetic nerves are those autonomic motor nerves that project from the brain and sacral (lower back) region of the spinal cord. Three important principles of the functions of the sympathetic and parasympathetic: (1) sympathetic nerves stimulate, organize, and mobilize energy resources in threatening situations, whereas parasympathetic nerves act to conserve energy. (2) each autonomic target organ receives opposing sympathetic and parasympathetic input, and its activity is thus controlled by relative levels of sympathetic and parasympathetic activity; and PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 15  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE (3) sympathetic changes are indicative of psychological arousal, whereas parasympathetic changes are indicative of psychological relaxation. Although these principles are generally correct, there are significant qualifications and exceptions to each of them. The majority of nerves in the peripheral nervous system originate in the spinal cord, however there are 12 pairs of cranial nerves that originate in the brain. From front to back, they are numbered in order. The olfactory nerves (I) and optic nerves (II) are entirely sensory nerves, however the majority of the cranial nerves contain both sensory and motor fibers. The vagus nerves (X) are the longest cranial nerves, carrying motor and sensory fibers to and from the gut. The cranial nerves' autonomic motor fibers are parasympathetic. Neurologists frequently analyze the functionality of the numerous cranial nerves as a basis for diagnosis. Disruptions of cranial nerve functioning provide great information regarding the location and degree of tumors and other types of brain pathology because the functions and placements of the cranial nerves are distinct. v Meninges The brain and spinal cord (the CNS) are the body's most well-protected organs. The three meninges (pronounced "men-IN-gees") are enclosed in bone and protected by three protective membranes: 1. The outer meninx (singular of meninges) is a tough membrane called the dura mater (tough mother). 2. Immediately inside the dura mater is the fine arachnoid membrane (spider-web-like membrane). 3. Beneath the arachnoid membrane is a space called the subarachnoid space, which contains many large blood vessels and cerebrospinal fluid; then comes the innermost meninx, the delicate pia mater (pious mother), which adheres to the surface of the CNS. v Ventricles and Cerebrospinal Fluid The subarachnoid space, the central canal of the spinal cord, and the cerebral ventricles of the brain are all filled with cerebrospinal fluid (CSF). The cerebral ventricles are the four large internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle. The central canal is a small central channel that runs the length of the spinal cord; the cerebral ventricles are the four large internal chambers of the brain: the two lateral ventricles, the third ventricle, and the fourth ventricle. A series of apertures connect the subarachnoid space, central canal, and cerebral ventricles, forming a single reservoir. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 16  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE II. Anatomy of the Central Nervous System v Spinal Cord The spinal cord is divided into two sections: an inner H- shaped gray matter core and a white matter surrounding area. 1. Gray matter is composed largely of cell bodies and unmyelinated interneurons. 2. White matter is composed largely of myelinated axons. (It is the myelin that gives the white matter its glossy white sheen.) The dorsal horns are the two dorsal arms of the spinal gray matter, and the ventral horns are the two ventral arms. At 31 distinct levels of the spine, two pairs of spinal nerves—one on the left and one on the right— are connected to the spinal cord. As the 62 spinal neurons approach the cord, they divide and their axons are connected to the cord via one of two roots: the dorsal root or the ventral root. All sensory (afferent) unipolar neurons in the dorsal root ganglia, whether somatic or autonomic, are sensory (afferent) unipolar neurons with their cell bodies grouped together immediately outside the cord to form the dorsal root ganglia. The dorsal horns of the spinal gray matter house many of their synaptic terminals. The neurons in the ventral root, on the other hand, are motor (efferent) multipolar neurons with cell bodies in the ventral horns. Those in the somatic nervous system project to skeletal muscles, while those in the autonomic nervous system project to ganglia, where they synapse on neurons in the autonomic nervous system. v Five Major Divisions of the Brain 1. Myelencephalon (or medulla), the most posterior division of the brain, is composed largely of tracts carrying signals between the rest of the brain and the body. The reticular formation is an intriguing portion of the myelencephalon from a psychological standpoint. It is a complicated network of roughly 100 small nuclei that runs from the posterior boundary of the myelencephalon to the anterior limit of the midbrain in the central core of the brain stem. It gets its name from its net-like appearance (reticulum literally means "little net"). Because sections of the reticular formation appear to have a role in arousal, it is sometimes referred to as the reticular activating system. The nuclei of the reticular formation, on the other hand, are involved in a wide range PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 17  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE of processes, including sleep, attention, movement, muscle tone maintenance, and different cardiac, circulatory, and respiratory responses. As a result, calling this collection of nuclei a system could be inaccurate. 2. Metencephalon creates a bulge, called the pons, on the brain stem’s ventral surface. The pons is one major division of the metencephalon; the other is the cerebellum (little brain). The cerebellum is a big, convoluted structure on the dorsal surface of the brain stem. It is a key sensory structure; injury to the cerebellum impairs one's capacity to precisely control and adjust motions to changing circumstances. However, the fact that cerebellar injury causes a wide range of cognitive abnormalities (for example, deficits in decision-making and language use) suggests that the functions of the cerebellum are not restricted to sensorimotor control. 3. Mesencephalon has two divisions: the tectum and the tegmentum. The tectum (roof) is the dorsal surface of the midbrain. In mammals, the tectum is composed of two pairs of bumps, the colliculi (little hills). The inferior colliculi, which make up the back pair, have an auditory function. The superior colliculi, or front pair, serve a visual-motor role, directing the body's direction toward or away from visual inputs. The tectum is frequently referred to as the optic tectum in lower vertebrates since its role is exclusively visual-motor. The tectum is separated from the mesencephalon by the tegmentum. The tegmentum comprises three colorful structures of importance to biopsychologists, in addition to the reticular formation and tracts of passage: the periaqueductal gray, the substantia nigra, and the red nucleus. 4. Diencephalon is composed of two structures: the thalamus and the hypothalamus. The thalamus is a two-lobed structure near the apex of the brain stem. One lobe sits on each side of the third ventricle, while the massa intermedia, which runs through the ventricle, connects the two lobes. White lamina (layers) made up of myelinated axons can be seen on the surface of the thalamus. The thalamus is made up of several distinct nuclei, the majority of which project to the cortex. The sensory relay nuclei—nuclei that receive signals from sensory receptors, interpret them, and then transmit them to the appropriate sections of sensory cortex—are the most well- understood thalamic nuclei. In the visual, auditory, and somatosensory systems, the lateral geniculate nuclei, medial geniculate nuclei, and ventral posterior nuclei, for example, are essential relay stations. Sensory relay nuclei are not one-way streets; they all get feedback from the cortical areas to which they transmit. Although less is known about the other thalamic nuclei, they all receive information from the cortex and project to other parts of the brain. The hypothalamus (hypo meaning "below") is placed directly below the anterior thalamus. It is crucial in the regulation of a variety of motivated actions (e.g., eating, sleep, and sexual behavior). It works in part by controlling the release of hormones from the pituitary gland, which is located on the ventral side of the brain and dangles from it. Pituitary gland literally means "snot gland," and it was discovered in a gelatinous state beneath the nose of an unembalmed cadaver, where it was mistakenly considered to be the principal source of nasal mucus. The optic chiasm and the mammillary bodies are two more structures that emerge on the inferior surface of the hypothalamus, in addition to the pituitary gland. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 18  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE 5. Telencephalon, the largest division of the human brain, mediates the brain’s most complex functions. It causes voluntary movement, analyzes sensory information, and mediates complex cognitive processes including learning, speaking, and problem solving. The cerebral cortex is a layer of tissue that covers the hemispheres of the brain (cerebral bark). The cerebral cortex is gray in color and is commonly referred to as the gray matter since it is primarily made up of tiny, unmyelinated neurons The layer beneath the cortex, on the other hand, is mostly made up of massive myelinated axons, which are white and are often referred to as the white matter. The cerebral cortex is very convoluted in humans (furrowed). The convolutions have the effect of expanding the quantity of cerebral cortex while keeping the brain's overall volume the same. Convoluted cortexes are not found in all mammals; most mammals are lissencephalic (smooth-brained). Fissures are the huge furrows in a convoluted cortex, while sulci are the little ones (singular sulcus). Gyri are the ridges that run between fissures and sulci (singular gyrus). The longest of the fissures, the longitudinal fissure, separates the cerebral hemispheres almost completely. A few tracts across the longitudinal fissure connect the cerebral hemispheres; these hemisphere-connecting tracts are known as cerebral commissures. Hemispheres or Four lobes: 1. The frontal lobe 2. The parietal lobe (pronounced “pa-RYE-e-tal”) 3. The temporal lobe, and 4. The occipital lobe (pronounced “okSIP-i-tal”). The hippocampus is a crucial part of the cortex that isn't neocortex and contains only three primary layers. In the medial temporal lobe, the hippocampus is placed at the medial margin of the cerebral cortex, where it folds back on itself. This folding results in a form that resembles a seahorse in cross section (hippocampus meaning "sea horse"). The hippocampus is involved in a variety of memory functions, including spatial memory. v Limbic System and Ganglia The limbic and basal ganglia systems provide a valuable framework for understanding the organization of various subcortical structures. The limbic system is a thalamic-circling circuit of midline regions (limbic meaning "ring"). The limbic system is involved in the regulation of motivated actions, including as flight, feeding, fighting, and sexual behavior. The amygdala, fornix, cingulate cortex, and septum are all major structures in the limbic system. The amygdala—the almond-shaped nucleus in the anterior temporal lobe (amygdala means "almond" and is pronounced "a-MIG-dah-lah")—is the starting point for tracing the limbic circuit. The hippocampus, which runs beneath the thalamus in the medial temporal lobe, is posterior to the amygdala. The PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 19  ARELLANO UNIVERSITY AB PSYCHOLOGY LEARNING MODULE cingulate cortex and the fornix are the next two structures in the ring. The cingulate cortex is a broad strip of cortex immediately superior to the corpus callosum on the medial surface of the cerebral hemispheres that encircles the dorsal thalamus (cingulate meaning "encircling"). The fornix, a prominent limbic tract that encircles the dorsal thalamus, begins at the dorsal end of the hippocampus and sweeps forward in an arc over the superior surface of the third ventricle, finishing in the septum and mammillary bodies (fornix meaning "arc"). At the anterior point of the cingulate cortex, the septum is a midline nucleus. The limbic ring is completed by many tracts that connect the septum and mammillary bodies to the amygdala and hippocampus. The hypothalamus is engaged in a range of motivated activities such as eating, sleeping, and sexual behavior, and the hippocampus is involved in some types of memory. On the other side, the amygdala is engaged in emotion, notably fear.. ü Why are neurons and synapses so vital to the nervous system's function, according to your readings and observations? ü What happens if one or more neurons or synapses are damaged? ü Hydrocephalus is a common congenital condition (present from birth). What do you think some of the long-term consequences of having hydrocephalus are? ü Consider this: “Whether or not you have contracted COVID-19, your brain has most definitely changed in the last few months. The infection can lead to a variety of neurological issues, as well as anxiety and sadness. The pandemic's isolation and concern can also affect our brain chemistry and lead to mood disorders.” For this module, the following assessment sources are recommended: 1. Attendance in class and involvement in class activities through the internet (such as recitation). 2. Class demeanor can also be seen (attentiveness and responsiveness during the lectures and activities) 3. Tasks, reaction papers, group work, reports, and the like must be submitted. 4. At the end of this module, there will be a quiz. PHYSIOLOGICAL PSYCHOLOGY (PSY 003) 20